Making a model is simple. You could use a number line or draw one out. I could help you, but I don't have a problem to work with...
Tell whether the two rates form a proportion . Please help me on number 16
Answer:36
Step-by-step explanation:

for every 7 students there are 4 girls, so for every 84 there must be 48
7*12=84
4*12=48
so, in all 84 students there are 48 girls
so amount of boys=84-48=36
there are 36 boys
7.16 dpollars for one candy bar